A storage system typically comprises one or more storage devices into which information may be entered, and from which information may be obtained, as desired. The storage system includes an operating system that functionally organizes the system by, inter alia, invoking operations in support of a storage service implemented by the system. The storage system may be implemented in accordance with a variety of storage architectures including, but not limited to, a network-attached storage environment, a storage area network, and a disk assembly directly attached to a client or host computer. The storage devices are typically disk drives organized as a disk array, wherein the term “disk” commonly describes a self-contained rotating magnetic media storage device. The term disk in this context is synonymous with hard disk drive (HDD) or direct access storage device (DASD).
In particular, in accordance with a network storage environment (generally), such as a Wide Area File System (WAFS) (or distributed file system) environment, information/data may be exchanged between one or more storage systems and one or more clients over a network of communication links. In such an environment, the storage system may be embodied as a server adapted to remotely serve and forward the data to the client. For example, the clients and servers may be separated by a wide area network (WAN), such as the Internet. As those skilled in the art will understand, communication between client and server therefore involves transmission of the data over the links, utilizing an associated amount of bandwidth on those links.
Generally, network communication links for data transmission may be expensive, as will be understood by those skilled in the art. For instance, certain monetary costs may be associated with installing links and/or using links (e.g., using a service provider's installed links), such as based on an amount of data transmission (e.g., band-width/throughput) over those links. Accordingly, network storage environments may employ one or more storage systems configured as network caches located at or near the clients to reduce the costs associated with data transmission. In particular, network caches, generally, may be used to “cache” (store) data locally to the client, such that when a client needs the data, the data need not traverse the network from the remote server if the data is already stored at the cache. Various configurations for network caches may include “write-through” (data is always written from the client “through” the cache to the server) and “write-back” caches (data is written from client “back to” the cache, and when necessary or when more optimal, written through to the server). In a write-through cache, only read performance is optimized, since each write operation or request from the client still traverses the network to the server. In a write-back cache, read and write performance is optimized with possibly fewer read and write requests traversing the network.
While network caches may advantageously optimize (i.e., reduce) the frequency of data transmissions, the actual transmission of data to the server still requires the utilization of bandwidth through the network. As mentioned above, however, the cost of the actual transmission of data through the network may generally be expensive. On the other hand, general-purpose computational processing speeds (e.g., for central processing units, CPUs) continue to increase and their prices decrease much more rapidly than do network connection speeds and prices. (In other words, it may be less expensive to purchase faster processing resources than to pay for faster/larger network connections.) As a result, it may thus be desirable to apply the relatively inexpensive resources (e.g., computational resources) toward optimizing bandwidth utilization over networks, particularly, for example, to reduce the actual data transmissions over expensive networks.